Electrophotosensitive member with multiple layers of amorphous silicon

Abstract

The present invention relates to a photosensitive member containing an a-Si:Ge layer with an a-Si intermediate layer. A photosensitive member containing a-Si:Ge has an excellent sensitivity to long wave light so that it is suitable for an electrophotographic system equipped with laser beam printer. However, the sensitivity of the member had not been improved because of their weak dark resistance and lower mobility of carrier in general. In the present invention, it is provided a photosensitive member having a-Si:Ge layer excellent in the sensitivity to long wave length by controlling the balance between the Ge content and the thickness of the a-Si:Ge layer and the concentration of oxygen or oxygen and carbon in the electroconductive layer.

What is claimed is: 
     
       1. An electrophotosensitive member which comprises: a conductive substrate;   an intermediate layer of amorphous silicon formed on said conductive substrate and including oxygen or carbon and an element in Group III A or VA of the Periodic Table in an amount to control the conductivity thereof to a polarity opposite to the polarity of charges induced in said substrate upon charging wherein said intermediate layer has a thickness of 30 Å to 2 μm and including 0.01 to 40 atomic % of said oxygen or 5 to 60 atomic % of said carbon; and   a photoconductive layer formed on said intermediate layer and including a first amorphous silicon layer, an amorphous silicon:germanium layer formed on said first amorphous silicon layer and having a composition represented by a-Si 1-x  :Ge x  H, the thickness d of said amorphous silicon:germanium layer satisfying a condition of 0.07≦dx 2  ≦0.90, and a second amorphous silicon layer formed on said amorphous silicon:germanium layer.   
     
     
       2. A photosensitive member as claimed in claim 1 wherein said Group III A element is boron and Group VA element is phosphorous. 
     
     
       3. A photosensitive member as claimed in claim 2 wherein boron is included in the amount of 10 to 20000 ppm in said intermediate layer for positive charging. 
     
     
       4. A photosensitive member as claimed in claim 2 wherein boron is included in the amount less than 20 ppm or phosphorous of less than 50 ppm in said intermediate layer for negative charging.